Preventing corrosion of ferrous metal surfaces in contact with water



United States Patent Ofice 2,9 9,338 Patented Aug. 16, 1960 PREVENTINGCORROSION OF FERROUS METAL SURFACES IN CONTACT WITH WATER 9 Claims. (Cl.212.7)

This invention relates to novel water soluble corrosion inhibitors andto the use therefor in preventing corrosion of metallic surfaces incontact with water.

Corrosion of metallic surfaces, particularly iron and steel, in contactwith fresh or salt water or various aqueous solutions, results in aserious economic loss. There is an urgent need for, and the presentinvention provides, improved Water soluble corrosion inhibitors whichwill retard and/or prevent such corrosion.

While the novel inhibitors of the present invention may be used in anysystem wherein water or aqueous solutions contact metallic surfaces, thefollowing specific examples are set forth as illustrative but notlimiting, instances in which the inhibitors of the present invention areuseful. Storage tanks, pipe lines, and the like containing petroleumoils and/or other organic compounds generally contain water which causescorrosion of the metallic surfaces. For example, in oil storage tanksthe water settles to the bottom and causes corrosion, of the internalsurface of the storage tank. The water soluble corrosion inhibitors ofthe present invention will dissolve in the water phase and will serve toretard and/ or prevent such corrosion. Another example is in the stamping, rolling, or other working of metal in which a water stream issprayed thereon or otherwise used as a coolant. Because these operationsare effected at high temperatures, the cooling water often causesextensive corrosion. Such corrosion is avoided by incorporating thecorrosion inhibitor of the present invention into the water spray.

Still another application is in the salt-ice water solutions used asrefrigerants, for example, in railroad cars, trucks, etc. When used inrailroad cars, the salt solution not only effects corrosion of therailroad cars but also drips onto the rails and causes corrosionthereof. It is readily seen that such corrosion is a serious economicproblem because it requires frequent replacement of rails, withconcurrent expense both in manpower and in material cost. Still otherapplications include boiler water, acid solutions such as picklingsolutions, etc.

. The novel corrosion inhibitors of the present inventionl are alkalimetal salts of aryl-l-desoxy-alduronic acids The aryl-l-desoxy-alduronicacid utilized in preparing the salt is selected so that the inhibitormolecule as a Whole is at least partially water soluble. This will bedescribed further in detail hereinafter in the specification. While notintended to be limited thereby, one explanation of the manner in whichthe present inhibitors function is that the relatively polar saltlinkage serves to attract the inhibitor to the metal surface where thehydrocarbon substituent of the alduronic acid covers the surface andexerts a protective action by keeping water soluble corrodents away fromthe metal. The hydroxy groups of the aryl-l-desoxy-alduronic acid renderthe in-,

hibitor compound at least partially water soluble so that it willpenetrate the Water film or layer covering the metallic surfaces andthereby will cover and protect the metallic surfaces in the mannerhereinbefore set forth.

Any suitable aryl-l-desoxy-alduronic acid may be used in preparing thealkali metal salts thereof and these may comprise themonoaryl-desoxy-alduronic acids, the diaryl-l-desoxy-alduronic acids, ormixtures thereof. In the preferred embodiment of the invention, thesearyll-desoxy-alduronic acids are di-aryl-l-desoxy-alduronic acids havingthe following formula:

H Aryl-(E-Aryl (CHOH) n C O OH in which at is an integer from 1 to about5 or more. The aryl groups may be unsubstituted or may be substituted byvarious hydrocarbon radicals such as alkyl, cycloalkyl, aryl, alkaryl,etc.

Illustrative preferred aryl-l-desoXy-alduronic acids for use inpreparing the alkali metal salt thereof for use as hereinbefore setforth include the following specific compounds:l-phenyl-l-desoxy-lyxuronic acid l,l-di-phenyl-l-desoXy-lyxuronic acidl-phenyl-l-desoxy-Xyluronic acid l,l-di-phenyl-l-desoxy-xyluronic acidl-phenyl-l-desoxy-arabinuronic acid 1,l-di-phenyl-l-desoxy-arabinuronicacid 1-phenyl-l-desoxy-riburonic acid 1,l-di-phenyl-l-desoXy-riburonicacid 1-phenyl-l-desoXy-taluronic acid 1,l-di-phenyl-l-desoxy-taluronicacid 1-phenyl-l-desoxy-galacturonic acidl,1-di-phenyl-l-desoxy-galacturonic acid l-phenyl-l-desoxy-iduronic acid1,l-di-phenyl-l-desoxy-iduronic acid l-phenyl-l-desoxy-guluronic acid1,1-di-phenyl-l-desoxy-guluronic acid 1-phenyl-l-desoxy-mannuronic acid1,l-di-phenyl-l-desoxy-mannuronic acid l-phenyl-l-desoxy-glucuronic acid1,1-di-phenyl-l-desoxy-glucuronic acid 1-phenyl-l-desoXy-altruronic acid1,1-di-phenyl-l-desoxy-altruronic acid l-phenyl-l-desoxy-alluronic acid1,1-di-phenyl-1-desoxy-alluronic acid l-p-tolyl-l-desoxy-lyxuronic acid1,1-di-(p-tolyl)-1-desoxy-lyxuronic acid l-p-tolyl-l-desoxy-Xyluronicacid 1, l-di- (p-tolyl) l-desoxy-xyluronic acid1-p-tolyl-l-desoxy-arabinuronic acid 1, 1 -di-(p-tolyl) -1-desoxy-arabinuronic acid 1-p-tolyl-l-desoXy-riburonic acid 1, l-di-(p-tolyl) -l-desoxy-riburonic acid l-p-tolyl-l-desoxy-taluronic acid1,1-di-(p-tolyl) -1-desoxy-taluronic acidl-p-tolyl-l-desoxy-galacturonic acid1,1-di-(p-tolyl)-1-desoxy-galacturonic acid l-p-tolyl-l-desoxy-iduronicacid 1,1-di-(p-tolyl)-1-desoxy-iduronic acidl-p-tolyl-l-desoxy-guluronic acid i a 3 i 1, l-di-(p-tolyl)-1-desoxy-guluronic acid l-p tolyl-l-desoxy-mannuronic acid1,1-di-(p-tolyl) -1-desoxy-mannuronic acid l-p-tolyl-l-desoxy-glucuronicacid 1,1-di-(p-tolyl) -1-desoxy-glucuronic acidIp-tolyl-l-desoxy-altruronic acid 1,1-di-(p-tolyl)-1-desoxy-altruronicacid l-p-tolyl-1-desoxy-alluronic acid 1,1-di-(p*tolyl)-1-desoxy-allurouic acid 1-(3,4-dimethylphenyl)-l-desoxylyxuronic acidI,1-di-(3,4-dimethylphenyl)-1-desoxy-lyxuronic acid1-(3,4-di-methylphenyl)-1-desoxy-xylur0nic acid I,1-di-( 3,4-dimethylphenyl) -1-desoxy-xyluronic acidl-(3,4-dimethylphenyl)-l-desoxy-arabinuronic acid I,1-di-(3,4-dimethylpheny1) -l-desoxy-arabinuronic acid1-(3,4-dimethylphenyl)-1-desoxy-riburonic acid 1,1-di-(3,4dimethy1'phenyl) l-desoxy-riburonic acid1-(3,4-dimethylphenyl)-1-dcsoxy-taluronic acid 1;l-di-(3,4dimethylphenyl)-1-desoxy-taluronic acid 1-( 3 ,4-dimethylphenyl) -l-desoxy-'galacturonic acid 1,1-di-(3 ,4-dimethylphenyl)-1-desoxy-galacturonic acid l-(3,4-dirnethylphenyl) -l-desoxy-iduronicacid 1,1-di-(3 ,4-dimethy1phenyl)-l-desoxy-iduronic' acidI-(SA-dimethylphenyl) -1-desoXy-guluronic acid1,1-di-(3,4-dimethylphenyl) -l-desoxy-guluronic acid 1-(3,4-dimethy1phenyl) -1-desoxy-mannuronic acid1,1-di-(3,4-dimethylphenyl)-1-desoxy-mannuronic acid 1- 3,4-dimethylphenyl) l-desoxy-glucuronic acid 1,1-di-(3 ,4 dimethylphenyl)l-desoxy-glucuronic acid 1-( 3,4-dimethylphenyl) -1-desoxy*altruronicacid 1,1-di- 3,4-dimethylphenyi) -1-desoxy-altruronic acid I (3,4-dimethylphenyl) -l-desoxy-alluronic acid 1,1-di-( 3,4-dimethylphenyl)-l-desoxy-alluronic acid 1p-ethylphenyl-l-desoxy-lyxuronic acid1,1-di-(p-ethylphenyl) -1-desoxy-lyxuronic acidl-p-ethylphenyl-l-desoxy-xyluronic acid 1, l -di-(p-ethylphenyl)-l-desoxy-xyluronic acid 1-p-ethylphenyl-1-desoxy-arabinuronic acid 1, l-di-(p-ethylphenyl) -l'-desoxy-arabinuronic acidI-p-ethylphenyl-1-desoxy-riburonic acid 1,1-di- (p-ethylpl1enyl) l-desoxy-riburonic acid 1-p-ethylphenyl-l-desoxy-taluronic acid1,1-di-(p-ethyphenyl)-l-desoXy-taluronic acid1-p-ethylphenyl-l-desoxy-galacturonic acid 1, l-di- (p-ethylphenyl) 1-desoxy-galacturonic acid l-pethyphenyl-l-desoxy-iduronic acid1,1-di-(p-ethylphenyl) -l-desoxy-iduronic acidl-p-ethylphenyl-l-desoxy-guluronic acid 1,1-di-(p-ethylphenyl)-1-desoxy-guluronic acid 1-p-ethylphenyl-l-desoxy-mannuronic acid1,1-di-(p-ethylphenyl) 1 -desoxy-mannuronic acid1-p-ethylphenyl-l-desoxyglucuronic acid 1 1 -di-(p-etl1ylphenyl) -1-desoXy-glucuronic acid 1-p-ethylphenyl-l-desoxy-altruronic acid1,1-di-(p-ethylphenyl) -1-desoxy-altruronic acidl-p-ethylphenyl-l-dcsoxy-alluronic acid 1,1-di-(p-ethylphenyl)-1-desoxy-alluronic acid.

It is understood that mixtures of aryland diaryl-ldesoxy-alduronic acidsmay be employed.

These ary1-l-desoxy-alduronic acids are formed by reacting uronic acidsand lactones thereof with aromatic hydrocarbons in the presence ofFriedel-Crafts metal halide catalysts, and particularly in the presenceof aluminum chloride. These condensation reactions are carried outconveniently in ordinary glass alkylation equipment using temperaturesof from about 20 C. to about 150 C., and preferably at temperatures offrom about 20 C. to about 100 C. While many of the condensationreactions are carried out at substantially atmospheric pressure, it maybe desirable in certain instances and with certain reactants to carryout the reaction in metal autoclaves at pressures up to 100 atmospheresor more. It is convenient in most instances to operate the equipmentutilized at the pressure generated by the reaction mixture and catalystcontained therein at the temperature utilized.

Aromatic hydrocarbons suitable for use in preparingaryl-l-desoxy-alduronic acids include compounds containing only carbonand hydrogen and in which there is retained at least one hydrogen atomattached to a carbon atom of the aromatic nucleus. Thus compounds suchas hexamethylbenzene cannot be utilized since such compounds areinoperative in preparing aryl-desoxyalduronic acids. Aromatichydrocarbons which may be utilized include those substituted with alkyl,aralkyl, aryl, alkaryl, cycloalkyl, alkylcycloalkyl, etc., radicalscontaining only carbon and hydrogen. Some utilizable aromatichydrocarbons may contain olefinic unsaturates or double bonds in theside chains or substituent groups containing only carbon and hydrogen,and while such compounds in general may be utilized, they are, however,not preferred. Thus, the preferred aromatic hydrocarbons areunsubstituted aromatic hydrocarbons, and aromatic hydrocarbonscontaining saturated or aromatic substituents containing only carbon andhydrogen. Utilizable aromatic hydrocarbons include benzene, toluene,ortho-xylene, meta-xylene, 1,2,3-trimethylbenzene, 1,2,4-trimethylbenzene, 1,3,5-trimethylbenzene, 1,2,3,4-tetramethylbenzene1,2,3,S-tctramethylbenzene, 1,2,4,5-tetramethylbenze,penta-methylbenzene, ethylbenzene, orthoethyltoluene, meta-ethyltoluene,para-ethyltoluene, npropylbenzene, isopropylbenzene, n-butylbenzene,isobutylbenzene, sec-butylbenzene, tert-butylbenzene, amylbenzenes,para-cymene, and higher molecular weight alkylaromatic hydrocarbons.Also, alkyl-aromatic hydrocarbons with long chain alkyl groups may beutilized. Such compounds are produced by the alkylation of aromatichydrocarbons with olefin polymers to yield such materials ashexylbenzenes, hexyltoluenes, nonylbenzenes, nonyltoluenes,dodecylbenzenes, dodecyltoluenes, etc. Other aromatic hydrocarbonssuitable for use in the preparation of aryl-l-desoxy-alduronic acidsinclude those with two or more aryl groups such as diphenyl, diphenylmethane, triphenyl methane, etc. Examples of suitable utilizablearomatic hydrocarbons which contain condensed benzene rings includenaphthalene, alpha-methylnaphthalene, beta-methylnaphthalene,phenanthrene, anthracene, naphthacene, pyrene, chrysene, rubrene, etc.Examples of other aromatic hydrocarbons include indan, fluorene,cyclopcntylbenzene, methylcyclopentylbenzene, cyclohexylbenzene, etc.

Alduronic acids and lactones thereof which are reacted with theabove-mentioned aromatic hydrocarbons in the presence of aFriedel-Crafts metal halide catalyst to produce aryl-l-desoxy-alduronicacids include the alpha and beta forms of riburonic acid, arabinuronicacid, xyluronic acid, lyxuronic acid, alluronic acid, altruronic acid,glucuronic acid, mannuronic acid, guluronic acid, iduronic acid,galacturonic acid, taluronic acid, etc. The alduronic acids are a groupof compounds which are obtainable by oxidation of the terminal alcoholgroups of aldoses. Suitable lactones of alduronic acids includeriburonolactone, arabinuronolactone, xyluronolactone, lyxuronolactone,alluronolactone, altruonolactone, glucuronolactone, mannuronolactone,guluronolactone, iduronolactone, galacturonolactone, taluronolactone,etc. These lactones of alduronic acids are spontaneously formed uponheating suitable alduronic acids in which formation of a 14 orgamma-lactone structure is possible, or in which formation of a l-5 ordelta-lactone structure is possible. Since the alduronic acids mustcontain at least 5 carbon atoms to be able to form gamma-lactones, thesugar acid lactones which may be utilized in preparingaryl-l-desoxy-alduronic acids will contain at least 5 carbon atoms.Sugar acid lactones containing 6 carbon atoms or more may also beutilized. When these uronic acids or lactones thereof react witharomatic hydrocarbons, they do so by reaction at the number 1 carbonatom.

As an example of such a preparation, glucuronolactone may be reactedwith an equimolecular proportion or less of benzene to givel-phenyl-l-desoxy-glucuronolactone or with more than an equimolecularproportion of benzene to give 1,l-diphenybl-desoxy-glucuronolactone. Thestructures of these l actone reaction products are represented asfollows:

Hydrolysis of these lactones results in the formation of the respectiveglucuronic acids of the following structures:

This hydrolysis can be carried out in either acidic or basic solutionsof the respective lactones.

The reaction of an aromatic hydrocarbon with an alduronic acid orlactone thereof maybe carried out, as set forth hereinabove, in thepresence of a Friedel- Crafts metal halide catalyst. Friedel-Craftsmetal halide catalysts which may be. employed are used in substantiallyanhydrous form or modified by means of an alcohol, an ether, an ester, anitroparaffin, etc., to give a catalyst of controlled activity, if sodesired. The preferred Friedel-Crafts metal halide catalyst issubstantially anhydrous aluminum chloride. Other Friedel-Crafts metalhalide catalysts which may be utilized but not necessarily withequivalent results are aluminum bromide, ferric chloride, ferricbromide, Zinc chloride, beryllium chloride, gallium chloride, titaniumtetrachloride, zirconium chloride, stannic chloride, etc.

, This reaction may be carried out by slowly adding a Fn'edel-Craftsmetal halide catalyst such as aluminum chloride to a stirred mixture .ofan aromatic hydrocarbon and an aldurom'c acid or lactone thereof whilemaintaining the reaction temperature at fromabout 20 C. to about 150 C.and preferably at from about 20 C. to about 100 C. After the reactionhas reached the desired degree of completion, the entire reactionmixture and catalyst maybe mixed with water or may be added to ice inorder to quench the activity of the catalyst and to permit separation ofthe organic reaction product and unreacted starting materials.

As hereinbefore set forth, the alkali metal salts ofaryll-desoxy-alduronic acids are prepared and utilized in the presentinvention. Suitable alkali metal salts include those selected fromlithium, sodium, potassium, rubidium, and cesium. Of these alkali metalsalts, the sodium salts are preferred. Typical sodium salts include thefollowing: the sodium salt of l-phenyl-l-desoxy-lyxuronic acid, thesodium salt of 1,l-di-phenyl-l-desoxy-lyxuronic acid, the sodium salt ofl-phenyl-l-desoxy-xyluronic acid, the

sodium salt of 1,l-di-phenyl-l-desoxy-xyluronic acid, the sodium salt ofl-phenyl-l-desoxy-arabinuronic acid, the sodium salt of1,1-di-phenyl-l-desoxy-arabinuronic acid, the sodium salt of 1-phenyll-desoxy-riburonic acid, the sodium salt ofl,l-di-phenyl-1-desoxy-riburonic acid, the sodium salt ofl-phenyl-l-desoxy-taluronic acid, the sodium salt ofl,l-di-phenyl-l-desoxy-taluronic acid, the sodium salt ofl-phenyl-l-desoxy-galacturonic acid, the sodium salt of1,1-di-phenyl-l-desoxy-galacturonic acid, the sodium salt ofl-phenyl-l-desoxy-iduronic acid, the sodium saltof1,l-di-pheny1-1-desoxy-iduronic acid, the sodium salt ofl-phenyl-l-desoxy-guluronic acid, the sodium salt ofl,l-di-phenyl-l-desoxy-guluronic acid, the sodium salt ofl-phenyl-l-desoxy-mannuronic acid, the sodium salt of1,l-di-phenyl-l-desoxy-marmuronic acid, the sodium salt ofl-phenyl-l-desoxy-glucuronic acid, the sodium salt of1,l-di-phenyl-l-desoxy-glucuronic acid, the sodium salt of1-phenyl-l-desoxy-altruronic acid, the sodium salt ofl,l-di-phenyl-l-desoXy-altruronic acid, the sodium salt ofl-phenyl-l-desoxy-alluronic acid, the sodium salt ofl,l-di-phenyl-l-desoxy-alluronic acid, the sodium salt ofl-p-tolyl-l-desoxy-lyxuronic acid, the sodium salt of 1,1-di-(p-tolyl)-l-desoxy-lyxuronic acid, the sodium salt of 1-p-tolyl-l-desoxy-xyluronic acid, the sodium salt of 1,1-di-(p-tolyl)-l-desoxy-xy1uronic acid, the sodium salt ofl-ptolyl-l-desoxy-arabinuronic acid, the sodium salt of 1,1-di-(p-tolyl)-l-desoxy-arabinuronic acid, the sodium salt of1-p-t0ly1-l-desoxy-riburonic acid, the sodium salt of 1,1-di-(p-tolyl)-l-desoxy-riburonic acid, the sodium salt ofl-ptolyl-l-desoxy-taluronic acid, the sodium salt of 1,1-di-(p-tolyl)-l-desoxy-taluronic acid, the sodium salt ofl-ptolyl-l-desoxy-galacturonic acid, the sodium salt of 1,1-di-(p-tolyl)-l-desoxy-ga1acturonic acid, the sodium salt of 1-p-tolyl-l-desoxy-iduronic acid, the sodium salt of l,1-di-(p-tolyl)-l-desoxy-iduronic acid, the sodium salt ofl-ptolyl-l-desoxy-guluronic acid, the sodium salt of1,'l-di-(ptolyl)-l-desoxy-guluronic acid, the sodium salt ofl-ptolyl-l-desoxy-mannuronic acid, the sodium salt of l,l-diphenyl)-l-des0xy-riburonic acid, the sodium salt of 1-(3,4-

dimethylphenyl)-1-desoxy-taluronic acid, the sodium salt ofl,l-di-(3,4-dimethylphenyl)-l-desoXy-talur0nic acid, the sodium salt ofl-(3,4-dimethylphenyl)-l-desoxygalacturonic acid, the sodium salt ofl,l-di-(3,4-dimethylphenyl)-l-desoxy-galacturonic acid, the sodium saltof l-(3,4-dimethylphenyl)-l-desoxy-iduronic acid, the sodi um salt of1,l-di-(3,4-dimethylphenyl)-l-desoxy-iduronic acid, the sodium salt of1-( 3,4-dimethylphenyl)-l-desoxyguluronic acid, the sodium salt ofl,l-di-(3,4-dimethylphenyl)-l-desoxy-guluronic acid, the sodium salt ofl-(3,4- dimethylphenyl)-l-desoxy-mannuronic acid, the sodium salt of1,l-di-(3,4-dimethylphenyl)-l-desoxy-mannuronic acid, the sodium salt ofl-(3,4-dimethylphenyl)-ldesoxyglucuronic acid, the sodium salt ofl,l'di-(3,4-dimethylphenyl)-l-desoxy-g1ucuronic acid, the sodium salt ofl- (3,4-dimethylphenyl) -1-desoxy-altruronic acid, the sodium salt of1,l-di(3,4-dimethylphenyl)-l-desoxy-altruronic acid, the sodium salt of1-( 3,4-dimethylphenyl)-l-desoxyalluronic acid, the sodium salt ofl,l-di-(3,4-dimethylphenyl)-l-desoxy-alluronic acid, the sodium salt ofl-pethylphenyl-l-desoxy-lyxuronicacid, the sodium salt of1,1-di-(p-ethylphenyl)-1-desoxy-lyxuronic acid, the sodium salt ofl-p-ethylphenyl-l-desoxy-xyluronic acid, the sodium salt of1,1-di(p-ethylphenyl)-1 desoxy-xyl1iroi1ic acid, the sodium salt ofl-p-ethylphenyl-l-desoXy-arabinuronic acid, the sodium salt of1,1-di-(p-ethylphenyl)-1- desoxy-arabinuronic acid, the sodium salt ofl-p-ethylphenyl-l-desoxy-riburonic acid, the sodium salt of 1,1-di-(p-ethylphenyl)-l-desoxy-riburonic acid, the sodium salt ofl-p-ethylphenyl-l-desoxy-taluronic acid, the sodium salt of1,1-di-(p-ethylphenyl)-1 desoxy-taluronic acid, the sodium salt of1-p-ethylphenyl-l-desoxy-galacturonic acid, the sodium salt of1,1-di-(p-ethylphenyl)-1-desoxy-galacturonic acid, the sodium salt ofl-p-ethylphenyl-ldesoxy-iduronic acid, the sodium salt of1,1-di-(p-ethylphenyl)-l-desoxy-iduronic acid, the sodium salt of1-pethylphenyl-ldesoxy-guluronic acid, the sodium salt of1,1-di-(p-ethylphenyl)-1-desoxy-guluronic acid, the sodium salt of1-p-ethylpheny1-l-desoxy-mannuronic acid, the sodium salt of1,1-di-(p-ethylphenyl)-l-desoxy-mannuronic acid, the sodium salt ofl-p-ethylphenyl-l-desoxyglucuronic acid, the sodium salt of1,l-di-(p-ethylphenyl)- l-dcsoxy-glucuronic acid, the sodium salt ofl-p-ethylphenyl-l-desoxy-altruronic acid, the sodium salt of 1,1-di-(p-ethylphenyl)-1-desoxy-altruronic acid, the sodium salt ofl-p-ethylphenyl-l-desoxy-alluronic acid, and the sodium salt of1,l-di-(p-ethylphenyl)-1-desoxy-alluronio acid.

The salt may be prepared in any suitable manner and, in general, isprepared by mixing the aryl-l-desoxyalduronic acid or lactone thereofand an alcoholic solution of sodium hydroxide or a sodium alcoholate atambient temperature, preferably with vigorous stiring. The salt isreadily prepared at room temperature, although slightly elevatedtemperatures may be preferred to speed up the reaction, whichtemperatures will generally not exceed about 100 C. Excessivetemperatures should be avoided as the temperature should be kept belowthat at which dehydration of the alduronic acid occurs and decompositionof the salt occurs. In general, it is preferred to utilize a solvent,either in forming a more fluid mixture of the acid and caustic beforemixing or during the mixing thereof, and to absorb the exothermic heatof reaction. Any suitable solvent may be employed. Ethanol andisopropanol are preferred alcohol solvents, although other alcoholsincluding methanol, n-propanol, butanols, pentanols, etc. may beutilized.

As hereinbefore set forth, the salts prepared in the above manner areutilized as water soluble corrosion inhibitors. The salt is incorporatedin water, aqueous solutions, or substrates containing water in asufficient concentration to etfectively retard corrosion of metallicsurfaces. Generally it will be utilized in a concentration of belowabout 1 percent by weight of the water, aqueous solution, or substratecontaining water, and usually in a concentration within the range offrom about 0.001 percent to about 1 percent or more, particularly fromabout 0.01 percent to about 0.5 percent by weight thereof, althoughhigher concentrations may be utilized when excessive corrosion isencountered. It is understood that the corrosion inhibitor may be usedin conjunction with other additives which are incorporated in thesubstrate for various reasons.

The following examples are introduced to illustrate further the noveltyand utility of the present invention but with no intention of undulylimiting the same.

EXAMPLE I In a one-liter alkylation fiask with a mercury sealed stirrerand reflux condenser, the following were contacted 4 hours at 70-80 C.:

Glucuronolactone grams 25 AlCl d0 93 Benzene cc 300 During thecontacting, 29 grams of HCl were evolved. The flask contents weredecomposed with ice and the following recovery noted exclusive ofunreacted benzene:

- Grams Hydrocarbon soluble oil 4.2 Water washed, cold water insolublesolid (A) 54 Pure compounds isolated 1 C18H18O5 Segment (B) contained 12grams of a component, (1), insoluble in cold water and crystallizingfrom hot water in needles forming star clusters. Dried on a filterpaper, these crystals showed a slight yellow sheen, and melted at178-180 C. These crystals dissolved immediately in NaOH solution but inconcentrated solution separated immediately as a sodium salt inthe formof short needles melting at 205-210 C. with decomposition. The sodiumsalt dissolved when diluted with water; when this solution wasacidified, no immediate precipitation occurred, but ml to 3 days,needles came out melting at 179-180" C., identical to the original. Thecompound burned with difliculty and difliculty was observed in carbonand hydrogen analysis in obtaining complete combustion.

Elementary analysis of (1) Percent Percent C H 68. 00 5. Found 68.21 5.as Calc. for 015111805 68. 78 5. 77

Thus, elementary analysis and chemical behavior of product 1) are inaccord with 1,1-di-phenyl-1-desoxy- .glucuronolactone:

H& OH 6H H5 OH 6011 6 ll 0 (1) 1,1-dipl1eny1-1-desoxy-hexuronolnctonoGlucuronolactone does not exist as the free acid, and the lactonestructure apparently went through the re action and subsequent waterrecrystallizations unchanged.

(2) CIBHZOOB Segment (C) crystallized from ether to crystals, designated(2), of melting point 138l39 C. This product had a fatty acid odor andgave a foamy solution in water. Like compound (1), it burned withdifficulty.

The yield of compound (2) could not be evaluated from. the dataavailable; its yield, however, was substan- HO lH HCOH1,l-di-phenyl-l-desoxy-hexuronic acid EXAMPLE II The sodium salt ofcompound 1, as described in Example I, was prepared by reaction of1,1-di-phenyl-ldesoxy-glucuronolactone with an ethanolic solution ofsodium hydroxide. The sodium salt is a solid and was recovered byfiltration. This sodium salt was tested as a corrosion inhibitor in 300cc. of a 5% sodium chloride solution. The concentration of this sodiumsalt of 1,1- di-phenyl-l-desoxy-glucuronic acid utilized was 0.05 weightpercent in the sodium chloride solution.

The corrosion inhibitor was evaluated by adding the 300 cc. of 5% sodiumchloride solution containing 0.05% of the inhibitor into a 600 cc.beaker which was stirred at 250 r.p.m. and air bubbled therethrough at arate of 5.6 liters per hour. On the bottomof the beaker in contact withthe brine solution was a mild steel strip one end of which was elevatedby a glass rod. Stirring and air introduction was continued for 6 hourstime. At the same time a duplicate experiment was carried out with noadded corrosion inhibitor in the brine solution. The iron strip in theblank or control experiment lost 22 milligrams in weight during the runin comparison to a Weight loss of 7.5 milligrams for the iron strip incontact with the brine solution and the sodium salt of1,l-di-phenyl-l-desoxy-glucuronic acid.

These experiments show that 1,1-di-phenyl-1-desoxyglucuronic acid in theform of its sodium salt is equivalent to or slightly better than sodiumnitrite, a well known corrosion inhibitor. The addition of the sameconcentration of sodium nitrite to a brine solution re sults in a weightloss of 8 milligrams in a comparable corrosion test. Water solublecorrosion inhibitors for brine solutions are particularly important foruse by railroads since brine which drips from refrigerator cars causesserious corrosion of railroad tracks. Also, wa-

ter soluble corrosion inhibitors are important in other diverse usessuch as in boiler water, etc.

We claim as our invention:

1. The method of retarding corrosion of a ferrous metal upon contactwith water which comprises elfecting said contact in the presence of awater soluble corrosion inhibitor comprising an alkali metal salt of anaryl-l-desoxy-alduronic acid.

2. A method of retarding corrosion of a ferrous metal upon contact withwater which comprises effecting said contact in the presence of a watersoluble corrosion inhibitor comprising an alkali metal salt of amonoaryll-desoxy-alduronic acid.

3. The method of retarding corrosion of a ferrous metal upon contactwith Water which comprises effecting said contact in the presence of awater soluble corrosion inhibitor comprising an alkali metal salt of adiaryl-l-desoxy-alduronic acid.

4. The method of retarding corrosion of a ferrous metal upon contactwith water which comprises efiecting said contact in the presence of a.water soluble corrosion inhibitor comprising the sodium salt of amonoaryl-l-desoxy-alduronic acid.

5. The method of retarding corrosion of a ferrous metal upon contactwith water which comprises effecting said contact in the presence of awater soluble corrosion inhibitor comprising the sodium salt of adiaryl-ldesoXy-alduronic acid.

6. The method of retarding corrosion of a ferrous metal upon contactwith water which comprises efiecting said contact in the presence of awater soluble corrosion inhibitor comprising the sodium salt of amonoaryI-Ldesoxy-glucuronic acid.

7. The method of retarding corrosion of a ferrous metal upon contactwith water which comprises effecting said contact in the presence of awater soluble corrosion inhibitor comprising the sodium salt of adiaryll-desoxy-glucuronic acid.

8. The method of retarding corrosion of a ferrous metal upon contactwith water which comprises effecting said contact in the presence of awater soluble corrosion inhibitor comprising the sodium salt ofl-phenyll-desoxy-glucuronic acid.

9. The method of retarding corrosion of a ferrous metal upon contactwith water which comprises eifecting sari'd contact in the presence of awater soluble corrosioninhibitor comprising the sodium salt of1,1-diphenyl-1- desoxy-glucuronic acid.

References Cited in the file of this patent UNITED STATES PATENTS

1. THE METHOD OF RETARDING CORROSION OF A FERROUS METAL UPON CONTACTWITH WATER WHICH COMPRISES EFFECTING SAID CONTACT IN THE PRESENCE OF AWATER SOLUBLE CORROSION INHIBITOR COMPRISING AN ALKALI METAL SALT OF ANARYL-1-DESOXY-ALDURONIC ACID.